Retroviral VpR/VpX protein (IPR000012)

Overlapping homologous superfamilies

Family relationships

Description

Human immunodeficiency virus (HIV) is the human retrovirus associated with AIDS (acquired immune deficiency syndrome), and SIV its simian counterpart. Three main groups of primate lentivirus are known, designated Human immunodeficiency virus 1 (HIV-1), Human immunodeficiency virus 2 (HIV-2)/Simian immunodeficiency virus - mac (SIVMAC)/Simian immunodeficiency virus - sm (SIVSM) and Simian immunodeficiency virus - agm (SIVAGM). Simian immunodeficiency virus - mnd (SIVMND) has been suggested to represent a fourth distinct group [PMID: 2797181]. These groups are believed to have diverged from a common ancestor long before the spread of AIDS in humans. Genetic variation in HIV-1 and HIV-2 has been studied extensively, and the nucleotide sequences reported for several strains [PMID: 2611042].

ORF analysis has revealed two open reading frames, yielding the so-called R- and X-ORF proteins, which show a high degree of sequence similarity.

Vpx plays a role in nuclear translocation of the viral pre-integration complex (PIC) and is thus required for the virus to infect non-dividing cells. Vpr also plays a role in nuclear translocation of the (PIC) and may target specific host proteins for degradation by the 26S proteasome. It acts by associating with the cellular CUL4A-DDB1 E3 ligase complex through direct interaction with host VPRPB/DCAF-1. This would result in cell cycle arrest or apoptosis in infected cells, creating a favourable environment for maximizing viral expression and production by rendering the HIV-1 LTR transcription more active.